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Study of heat transfer characteristics of impinging air jet using pressure and temperature sensitive luminescent paint.

机译：使用压力和温度敏感的发光涂料研究撞击空气的传热特性。

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摘要

Luminescent coating measurement system is a relatively new technology for quantitative pressure and temperature measurement. Usually referred to as Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP), luminescent coatings contain sensor molecules, which undergoes a luminescent transition when excited with light of proper wavelength. The reaction is pressure and/or temperature sensitive. The image of TSP or PSP coated model surface can be captured with a scientific grade camera and then processed to obtain full field temperature and pressure distribution with very high fidelity. The preparation time of the technique is short. The measurement system offers an economic alternative to conventional testing methods using large number of pressure taps and thermocouples. The purpose of the experiment in this thesis is to take the benefits of the TSP and PSP technique, develop a well-controlled process and then apply the technique for a fundamental study on jet impingement heat transfer.; First, Uni-Coat TSP and Binary-FIB PSP purchased from ISSI Inc. are calibrated to high accuracy. The calibration uncertainty of TSP and PSP are found to be +/-0.93°C and +/-0.12 psi over temperature and pressure ranges of 22 to 90°C and 5 to 14.7 psia, respectively. The photodegradation of TSP is then investigated with the same calibration system. The photodegradation refers to the phenomenon of decreasing emission intensity as the luminescent paint is exposed to the illumination light during testing. It was found that photodegradation rate is a strong function of temperature and the optical power of illumination lighting. The correlation developed in this work is expected to compensate the degradation of TSP to achieve high measurement accuracy.; Both TSP and PSP were then applied in the flow and heat transfer measurement of single round impinging air jet. Various separation distance (Z/D) and jet Reynolds number are tested. Pressure measurement on the jet impinged target surface using PSP clearly shows the boundary of jet impingement zone, which broadens with separation distance. In heat transfer experiment using TSP, the "second peak" in local heat transfer occurring at radial distance r/D around 2 is clearly observed when the separation distance Z/D is shorter than the length of jet potential core. The slight variation in radial location and the amplitude of the "second peak" are captured as Z/D and jet Reynolds number change. The optimum Z/D of stagnation point heat transfer is found to be around 5. The effect of jet nozzle configuration is investigated. It is found that the heat transfer rate associated with "tube jet" is generally higher than that of "plate jet". The difference in heat transfer between the two jet configurations is related to the weaker entrainment effect associated with "plate jet", where the entrainment of surrounding air is confined by the injection plate, especially under small Z/D circumstances. When compared with the benchmark data in the literature, the averaged heat transfer data of "tube jet" matches the empirical data better than those of "plate jet". The maximum difference is 3.3% for tube jet versus 15.4% for plate jet at Reynolds number of 60000 and Z/D of 5. The effect of surface roughness on jet impingement heat transfer is also studied. Heat transfer can be significantly increased by the enhanced roughness of the target surface. The largest roughness effect is achieved near stagnation point at high jet Reynolds number. Compared to the heat transfer to a smooth plate, as high as 30.9% increase in area-averaged Nusselt number is observed over a rough surface at r/D=1.5 and jet Reynolds number of 60000.; The most significant advance of the present work is that both temperature and pressure measurement be obtained with the same measurement system and with accuracy comparable to traditional testing methods. The procedures that were employed in this work should be easy to apply in any universi
机译：发光涂层测量系统是用于定量压力和温度测量的相对较新的技术。通常称为压力敏感涂料（PSP）和温度敏感涂料（TSP）的发光涂层包含传感器分子，当用适当波长的光激发时，它们会经历发光转变。该反应对压力和/或温度敏感。 TSP或PSP涂层模型表面的图像可以用科学级相机捕获，然后进行处理以获得非常高保真度的全场温度和压力分布。该技术的准备时间短。该测量系统为使用大量压力抽头和热电偶的常规测试方法提供了经济的选择。本文的实验目的是利用TSP和PSP技术的优势，开发一个可控的过程，然后将该技术应用于射流冲击传热的基础研究。首先，对购自ISSI Inc.的Uni-Coat TSP和Binary-FIB PSP进行高精度校准。在22至90°C和5至14.7 psia的温度和压力范围内，TSP和PSP的校准不确定度分别为+/- 0.93°C和+/- 0.12 psi。然后使用相同的校准系统研究TSP的光降解。光降解是指在测试过程中发光涂料暴露于照明光时发射强度降低的现象。发现光降解速率是温度和照明照明的光功率的强函数。这项工作中发展的相关性有望补偿TSP的降级，以实现高测量精度。然后将TSP和PSP应用于单次圆形撞击空气流的流动和传热测量。测试了各种间隔距离（Z / D）和射流雷诺数。使用PSP对射流撞击的目标表面进行压力测量可以清楚地显示射流撞击区域的边界，该边界会随着分离距离而变宽。在使用TSP的传热实验中，当分隔距离Z / D短于射流电芯的长度时，可以清楚地观察到在径向距离r / D大约2处发生的局部传热的“第二峰值”。径向位置的微小变化和“第二个峰值”的幅度随Z / D和射流雷诺数变化而捕获。发现停滞点传热的最佳Z / D约为5。研究了喷嘴结构的影响。已经发现，与“管式射流”相关的传热速率通常高于“板式射流”。两种射流配置之间的传热差异与“板式射流”相关的较弱的夹带作用有关，在这种情况下，周围空气的夹带是由注入板限制的，尤其是在小Z / D环境下。当与文献中的基准数据进行比较时，“管式射流”的平均传热数据比“板式射流”的经验数据更好地匹配了经验数据。雷诺数为60000且Z / D为5时，管式射流的最大差异为3.3％，而板式射流的最大差异为15.4％。还研究了表面粗糙度对射流撞击传热的影响。通过提高目标表面的粗糙度，可以显着提高热传递。在高喷射雷诺数下，在停滞点附近可获得最大的粗糙度效果。与热传递到光滑板相比，在r / D = 1.5和喷射雷诺数为60000时，在粗糙表面上观察到的面积平均努塞尔数增加了30.9％。当前工作的最重要进展是，可以使用相同的测量系统获得温度和压力测量值，并且其精度可与传统测试方法相比。这项工作中采用的程序应易于在任何大学中应用

著录项

  • 作者

    Liu, Quan.;

  • 作者单位

    University of Central Florida.;

  • 授予单位 University of Central Florida.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 192 p.
  • 总页数 192
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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